Partial fix for LP-1351089
LP-1351089 :: Isolate tests from users BASH_ENV
Add comments per suggestion from @axw
Add reviewing checklist to docs/contributions. There is some overlap with the style guide. Where the style guide aims to be descriptive, this document is simply a list of questions for the reviewer to ask when when reading a PR.
Merge branch 'master' into review-doc
Merge pull request #441 from waigani/review-doc

Add reviewing checklist to docs/contributions.

There is some overlap with the style guide. Where the style guide aims to be descriptive, this document is simply a list of questions for the reviewer to ask when when reading a PR.
Merge pull request #454 from johnweldon/lp-1351089-isolate

LP-1351089 :: Isolate tests from users BASH_ENV

By suppressing bash from loading the BASH_ENV files
Merge pull request #450 from johnweldon/lp-1351089

Partial fix for LP-1351089

If the environment has `set -o noclobber` then `cat > $TMPFILE` will fail if $TMPFILE exists.

The test referenced in [lp-1351089](https://bugs.launchpad.net/juju-core/+bug/1351089) should still be isolated better from the environment, but this seems like a good change to make anyway.